As an alternative to invasive-type surgeries whereby a physician creates an incision to access a desired location in the patient's body, many minimally invasive surgeries and in vivo examinations are being performed using catheters that are inserted into a patient's body. With a catheter in place, medical devices are routed through a lumen in the catheter in order to obtain tissue samples, perform a surgical procedure or diagnose tissue in a patient's body.
To insert a catheter, many physicians first use a guidewire that is routed to a desired location in the patient's body. The guidewire then acts as a rail over which catheters or other medical devices can be easily routed to the desired location.
FIG. 1 illustrates a conventional guidewire and rapid exchange-type catheter. A catheter 10 includes a working lumen 12 through which a medical device can be inserted, and a guidewire lumen 14 through which a guidewire 18 is passed. The catheter 10 can be threaded over the guidewire 18 by inserting the proximal end of the guidewire into the distal end of the guidewire lumen 14. Alternatively, the distal end of the guidewire 18 can be inserted into the proximal end of the lumen 14 by threading it through an introducer 20 at the proximal end of the catheter. The introducer 20 acts as a funnel to guide the distal tip of the guidewire into the guidewire lumen 14.
In some instances, it is desirable to exchange the catheter 10 for another catheter while leaving the guidewire 18 in place. In order to avoid removing the guidewire 18, the proximal end of the guidewire is held stationary while the catheter 10 is removed. If a conventional catheter is used, the guidewire must be substantially longer than the catheter, in order to pull the catheter off the guidewire. Such long guidewires may be unwieldy in the operating room.
To reduce the need for such long guidewires, many catheters include a rapid exchange-type feature whereby the majority of guidewire lumen 14 is formed as a channel 16 having a slit that extends along a length of the catheter 10. The catheter can be removed from the guidewire by pulling the guidewire through the slit in channel 16 up to the point where the channel becomes an enclosed lumen towards the distal end of the catheter. The remaining distal section of the guidewire lumen can then be pulled over the proximal end of the guidewire. Rapid exchange-type catheters and their use are considered to be well known to those of ordinary skill in the medical device arts.
In order to remove a guidewire from a rapid exchange-type catheter when backloading, the proximal end of the guidewire is forced through the slit in guidewire channel 16. This is typically accomplished by bending the catheter 10 in the region of the proximal end of the guidewire such that the proximal tip pokes through the slit in the channel 16. Many modern guidewires include tips of differing flexibilities at their proximal and distal ends, thereby giving the physician the option of adjusting the flexibility depending on which end of the guidewire is inserted into the patient. However, such flexible tips are difficult to use with rapid exchange-type catheters because they are not stiff enough to be forced through the slit in the channel 16 without severely bending and possibly kinking the catheter. Therefore, there is a need for a technique to use rapid exchange-type catheters with guidewires having flexible proximal ends.